Improvement in ponton coffer-dams



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v1, NAPlen. Punten Cuffer-Dams.- N0. 146,775. Patented Jan.27,1874.l

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Panton `Suffer-Dams.

N0. 146,775. PatentedJan.2l.7,1`874.

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NPuntun Suffer-Dams.

No. r46,775.

Patented 1an. 27,1874.`

Img! Sew'am of' ,Dam .swwing Wall built Uf-1 M .H'igb Waller (19 mae 1 2) lNITED STATES ATENT OFFrcn.

` JOHN NAPIER, OF LONDON, ENGLAND.

IMPROVEMENT IN PONTON COFFER'DAMS.

Specification formirg part of Letters Patent No. 146,775, dated January 27, 1974; application tiled October 22, 1873. Y

To all whom 'it may concern:

Be it known that I, JOHN NAPIER, of 18 Finsbury Circus, in the city of London, England, a subject of the Queen of Great Britain, have invented or discovered new and useful Improvements in Apparatus to be used in lieu of a (iOffer-Dam for making excavationsunder Water, and for excluding water for other purposes; and I, the said JOHN N APIER, do hereby declare the nature of the said invention, and in what manner the same is to be perl formed, to be particularlydescribed and as Aused and to be removed after use. Around the bottom of the ponton a keel-like ridge is formed, which is sharp at its lower edge. The ponton, having been oated to the place where it is required for use, is allowed to settle down until it rests on ythe bottom, and the sharp keel then penetra-tes to a sufficient depth to cut oif all communication between the exterior water and the space inclosed by the ponton. In order to cause the keel to penetrate to a sufficient depth, the compartments around the central opening are lled with water. Pumps are provided to pump out the water from the space inclosed by the ponton, and the same pumps may be employed, if necessary, in filling and emptying the compartments of the ponton. Where there is sufficient tide, the water can be run out and Will not require pumping. In some cases I make the ponton three-sided, so that when a portion of a wall has been built up within it it may be floated olf to sufcient distance to enable the work to be continued, whereas otherwise-that is to say, when the ponton is four-sided-the Work must not be carried so high as to prevent the ponton being floated away over the top of the work. The sides of the ponton are firmly braced together by girders, which, if desired,

same, and Fig. 3 shows a transverse section of the arrangement.

rlhe ponton-dam is con structed with a stron g frame of angle or T iron, which is plated'over in the wayin which an iron ship is constructed. The internal capacity al of the ponton-dam is divided into several water-tightcompartments, into which, by suitable valves worked from the deck, water can be admitted, and it can also be pumped out or allowed to escape from these compartments. When the ponton-dam l is to be conveyed to the place where it is required for use, it is floated and towed to its place; then water is admitted to the compart ments, and it settles.. down onto the bottom,

which, if of mud or clay, will prove the most suitabley ground for the apparatus to work in; but such a bottom is by no means absolutely necessary, as by excavating round the inside edge of the keel it can in other materials be made to sink to any depth required. The weight of the structure causes the sharp, keellike ridge a2, which is formed all around the bottom, to penetrate the soil and cut ott' communication between the water in the space a3, which the ponton-dam incloses, and the water outside, except by pipes or passages provided for the purpose, which can at pleasure be closed by valves. As the tide falls, the water is allowed to run out of the space a3 by these pipes v or passages, which are then closed; or, when necessary, the water is pumped out. The eX- cavation for the foundations 1s then made, and

afterward the wall is built up until it is ,above the low-water level. The compartments a1 of the dam are now emptied, and the water is excluded from them, while it is allowed to flow freely into the space a3. Thus the structure ,is caused to iioat with the rising tide until it has risen over the top of the wall, when it is hauled awav and can at once be ad'usted to a new position to construct another length of the wall. a4 a4 are movable beams, connect ing the two sides of the ponton-dam so as to give it a rigidity and stiffness. rllhe cutting keel or ridge a2 is very strongly framed, so that it may not be liable to be distorted by any obstacles with which it may meet. The portions of wall thus constructed may be connected without difficulty by piling the spaces between them on either side, as is shown at b, so as to form a small dam, within which the masonry is laid. Usually a single tide will sufiice to complete, in this manner, the connection between two lengths of walls built by means of the ponton-dam, as already described. The sectional form of a ponton-dam may be varied thus: Sections G and H are forms which are suitable where a wide excavation is,

required, as in dredging operations. As represented in these figures, the cutting-keel is constructed of strong plates supported by anglepieces at intervals.

ln some cases I form the ponton-dam with three sides only. Fig. 4 is a plan illustrating this arrangement. Fig. 5 is an elevation, partly in section 5 and Fig. 6 is a section taken on the line c d in Fig. 4. In this case a tiebeam, a5, is used to connect and support the two free extremities of the structure. This tie-beam, as well as the smaller ties a4 a4, is placed at such a height as not to interfere with the work to be carried on within the space a3. Then using a ponton-dam of this construction, the wall can be carried up farther than when the ponton-dam is so constructed as completely to inclose the space a3. Vhen one sec` tion of the wall has been completed, the threesided ponton-dam'is oated and adjusted to the end of the wall so as just to overlap it, in the manner shown by the drawings. The pon ton-dam, when so adjusted, is caused to settle down onto the bottom, in the manner already described, and piling, as shown at c @,is then driven between the wall and the extremities of the ponton-dam, so as to complete the inclosure of thespace a3.

These pontondams may, for convenience of transport, be constructed in parts capable of being bolted together when required for use. This arrangement will also admit of the use of the pontons, in the manner illustrated by Figs.

7 and 8, in examining the foundations of walls.

Fig. 7 is a plan, and Fig. Sis a transverse section taken on the line e f in Fig. 7.

Filing is employed between the wall and the ponton-dam, as already described in respect to Figs. 4, 5, and 6, and in this manner the space a3 is inclosed at each end.

Having thus described. the nature of my said invention, and the manner of performing the same, I would have itunderstood that I claim- The apparatus for making excavations under water, and for excluding water for other purposes, such apparatus vconsisting of a ponton.- dam with a sharp, keel-like ridge, adapted to penetrate the bottom on which it is allowed to rest, and with compartments, which may be emptied or fllled to float or. sink the apparatus, substantially as described.

JOHN NAFIER.

Witnesses:

G. F. W ARREN, WILMER M. HARRIS, ,Both of No. 17 GmceCm-i'071 Street, Loudon. 

